Recently, silicon has become a primary candidate to replace the material used as the substrate for making magnetic recording head sliders. This has been facilitated by the use of a new parting process, a dry etch process known as Deep Reactive Ion Etching (DRIE), to form the slider bodies from the finished wafer. Essentially, using DRIE the sliders are parted from each other on the wafer prior to being detached therefrom.
DRIE uses a high density plasma to achieve a high aspect ratio etch, which exceeds the aspect ratio available using diamond saws. This high aspect ratio etch translates into a reduced “kerf”, which in turn allows a higher packing density of sliders on the wafer and reduced manufacturing costs. Furthermore, because the etching process is entirely chemical in nature, there is no localized cracking or mechanical damage generated in the sliders. Diamond saws, on the other hand, generate cracks in the sliders or groups of sliders cut from the wafer. The cracks can then, over time, propagate and produce particles which can cause failure in a magnetic disk drive.
The shedding of particles from sliders, and the resultant head-disk interaction (HDI) which produces scratches in the magnetic disk and damage to the data therein, is an ongoing concern for the slider recording head and magnetic disks. It is reasonable to expect that HDI will also be of concern for the interaction of the silicon slider with magnetic disks.
As described above, the elimination of mechanical damage in the parting operation for silicon sliders has been well addressed by the DRIE process; however, the present invention understands that although the as-etched surfaces are quite smooth, some residual roughness of a short length scale may be generated on all four processed surfaces of the slider, namely, the “flex” surface, the air bearing surface (ABS), and the surfaces commonly referred to as SW1 and SW2. As further recognized herein, the roughness is largely the same in character on all four sides. The present invention critically understands that the residual peak-to-valley roughness, measured over the full slider face, may be on the order of two microns, and can result in protrusions that are one to four microns wide.
Currently, the shedding of particles in magnetic disk drive sliders for both AlTiC sliders and silicon sliders is undertaken by lapping the ABS surface, and then using numerous additional cleaning processes prior to installation in a drive. Nonetheless, the present invention critically recognizes that particle shedding remains a reliability concern, and that using numerous processes for the same task cascades costs. Having made this critical observation, the invention disclosed herein is provided.